Agrico Chemical Company

Freeport-mcmoran Resource Partners, Limited Partnership

Freeport Mcmoran Resource Partners

Charles W Weston

John W Wen

Frederick S Mandel

Willis L Thornsberry, Jr

Allen R Sutton

Padraic S O'Neill

Lawrence A Peacock

Michael A Murray

Kyle D Clevenger

Richard L Balser

Jesse S Chang

An improved fluid urea-containing fertilizer composition is disclosed; the composition is essentially comprised of an aqueous solution of urea, ammonium nitrate, N-(n-butyl)thiophosphoric triamide (NBPT), dicyandiamide (DCD), and may optionally also contain a clay as a suspending agent. The fluid fertilizer composition can be applied to a field crop in a single application and will nevertheless supply sufficient nitrogen to the plants throughout their growth and maturing cycles. As a result, the improved composition increases the nitrogen uptake efficiency of plants, enhances crop yields, and minimizes the loss of nitrogen from the soil. The NBPT is incorporated into the fluid fertilizer composition by blending a concentrated solution of N-(n-butyl)thiophosphoric triamide in a solvent selected from the group consisting of liquid amides such as an N-alkyl pyrrolidone directly with an aqueous solution of urea and ammonium nitrate, optionally also containing a suspending agent and commonly referred to in the fertilizer trade as UAN; the DCD may be added to the UAN fluid as a solid, a suspension, or in dissolved form along with the NBPT.

Fluid urea-containing fertilizer

An improved homogenous granular fertilizer composition is disclosed; the composition is comprised primarily of urea, N-(n-butyl)thiophosphoric triamide (NBPT), and dicyandiamide (DCD). The composition of this invention can be applied to a field crop in a single surface application and will nevertheless supply sufficient nitrogen to the plants throughout their growth and maturing cycles. The new improved composition increases the nitrogen uptake by plants, enhances crop yields, and minimizes the loss of both ammonium nitrogen and nitrate nitrogen from the soil. The NBPT is incorporated into the homogenous granular fertilizer composition of this invention by blending a concentrated solution of NBPT in a solvent selected from the group consisting of liquid amides, 2-pyrrolidone, and N-alkyl 2-pyrrolidones directly into molten urea prior to its granulation; the DCD may be added to the urea melt as a solid or in dissolved form along with the NBPT.

Granular urea-based fertilizer

This invention provides a method for removing aluminum contamination from phosphoric acid during the acidulation of phosphate rock with sulfuric acid in the presence of recycled phosphoric acid. The method of this invention involves the addition of acid soluble silica to the acidulation slurry and calls for maintaining the molar ratio of non-fluosilicate fluoride (i.e. fluoride not complexed with silica) to aluminum in the liquid phase of the acidulation slurry between 2.5 and 5.0. These conditions favor the precipitation of aluminum as calcium tetrafluoaluminate dihydrate and enable the co-removal of this compound by filtration with by-product gypsum. This invention is particularily suitable for the processing of phosphate rocks with high iron and aluminum contents, such as the nonsedimentary phosphate rocks occurring in Sri Lanka.

Removal of aluminum contamination during production of phosphoric acid

A two-stage process for treating acidic gypsum pond water for reuse or for discharge is disclosed. The first stage blends raw acidic pond water with recycled lime-treated slurry from the second stage of the process. The resulting elevation in pH causes CaF.sub.2 and SiO.sub.2 to precipitate and the precipitated material is discarded onto the gypsum storage area. The supernatant water can be used in the wet grinding mill and/or further treated in a second stage with lime to produce treated water which meets government environment standards for discharge. The slurry of calcium phosphate formed in the second (liming) stage is recycled to the first stage.

Process for treating pond water

An improved aqueous nitrogen fertilizer has been developed that increases first-year nitrogen uptake efficiency to plants. It is also a nitrogen fertilizer with features to minimize exposure to nitrogen loss. It is a nitrogen fertilizer consisting of urea, dicyandiamide, ammonium thiosulfate, and optionally a phosphate compound which is preferably an ammonium phosphate compound. This composition can contain a dye and/or various mineral micronutrients. This homogeneous granular fertilizer can be applied to a field crop in a single application and is available to the growing plant throughout its growth and maturing cycle. The homogeneous granular fertilizer composition is conveniently prepared by the addition of a dicyandiamide, and a solution of ammonium thiosulfate to molten urea. A phosphate compound and preferably ammonium polyphosphate, would be added along with these components.

Homogeneous granular nitrogen fertilizer

A process for the recovery of sulfur from sulfur-bearing ores employing an aqueous leaching solution containing calcium monosulfide, calcium hydrosulfide or mixtures of such calcium sulfide species. The sulfur ore is contacted in an extraction zone with the aqueous leaching solution under conditions to solubilize sulfur from the ore in the form of calcium polysulfide. Preferably, the extraction step is carried out at an elevated temperature. The loaded leaching solution is recovered from the extraction zone and applied to a sulfur-production zone. Here the loaded solution is contacted with hydrogen sulfide under conditions to react the hydrogen sulfide with the calcium polysulfide to produce calcium hydrosulfide and elemental sulfur. The calcium hydrosulfide solution is recycled for use as leaching solution in the sulfur extraction zone.

Sulfur recovery process

A carbonaceous material, such as coal, is gasified through the catalytic action of an alkali metal salt. The alkali metal is provided as a sulfate which is converted to a sulfide during gasification. In one embodiment, sodium sulfate is converted to sodium sulfide at a temperature effective to form a transitory melt condition at an interface which obtains coal gasification at relatively low temperatures and material residence times for the reaction. An alkaline earth sulfate, such as a gypsum, may be concurrently converted to a sulfide during gasification. The alkali metal sulfide may then be regenerated to a sulfate for process reuse while converting the alkaline earth to a carbonate for environmentally safe disposal with concurrent recovery of valuable sulfur. The evolved carbon gases may be used for fuel, for process feed chemicals, or the like.

Sulfate reduction process useful in coal gasification

Phosphoric acid is produced by the wet process from phosphate rock containing fluochlorapatite. The rock is ground in a crusher (10) to a size such that from about 50% to about 90% by weight will be passed by a -200 mesh U.S.S. sieve before being passed into a digestor (14) where it is mixed with sulfuric acid and recycled phosphoric acid to form a slurry. A suitable reductant such as sulphur dioxide is added to the slurry to maintain the oxidation-reduction potential in the range from about +150 mv to about +750 mv. The gypsum by-products are then removed from the slurry at filter (16) and a portion of the acid is recycled to digestor (14). The remaining acid is either concentrated and further processed to make fertilizers or is further processed via path (20) to remove aluminum and/or iron impurities. Select amounts of fluoride and sodium containing compounds are added to the acid in a stirred reactor (30) to cause precipitation of aluminum, principally as Na.sub.2 AlF.sub.5. After about 15 to about 60 minutes of stirring at a temperature below about 70.degree. C., the precipitate is removed at filter (32) where the acid is either processed to make fertilizer or subjected to additional processing to remove iron contaminants. Iron contaminants are removed from the filter acid or from aluminum removed acid from filter (32) by adding sufficient ammonia to the acid in a stirring reactor (40) to cause precipitation of iron principally as NH.sub.4 Fe.sub.2 H.sub.8 (PO.sub.4).sub.5.AH.sub.2 O, to reduce the level of iron to desired levels. After aging in the reactor from about 2 to about 24 hours at a temperature below the boiling point of the acid, the precipitate is removed at filter (42) and the resulting iron reduced acid is concentrated and subjected to conventional processing for making fertilizers.

Process for producing wet process phosphoric acid from phosphate rocks

An economical process for treating the acidic pond water to be used in the internal grinding circuit of a wet process phosphoric acid plant. Water is added to a quantity of a hydratable calcium compound, such as quicklime, to form a slaked lime slurry. A sufficient quantity of the slaked lime slurry is reacted with the acidic pond water to obtain a low fluoride solution having a fluoride content less than about 300 ppm and a pH in the range from about 2.0 to about 3.0, preferentially in the range 2.6-2.8, whereby calcium fluoride is precipitated. The precipitate bearing low fluoride solution is then clarified and the precipitate removed as underflow from the clarifier and transferred to the gypsum pond. In the preferred embodiment, the clarified low fluoride water is fed to the ball mill and is mixed with the phosphate rock being crushed. Removal of fluoride from the pond water solution reduced the 'blinding effect' of the fluoride and permits the calcium carbonate in the phosphate rock to neutralized the acidic pond water to minimize corrosion in the mill and elsewhere in the plant. The resulting slurry from the ball mill is about 55% to 65% solids and ranges in pH range from about 5.0 to about 5.5. The phosphate rock slurry is then passed through a hydroclone circuit where the larger (heavier) particles are removed for recycling to the ball mill and the remaining lightweight particles in the rock slurry are processed by phosphoric acid plant.

Neutralization of cooling pond water in phosphoric acid plants

A process for the manufacture of phosphoric acid from phosphate rock is provided. The phosphate rock is digested or acidulated with an acid solution containing oxalic acid to produce phosphoric acid and calcium oxalate. Useful by-products are also formed and include calcium carbonate and ammonium oxalate. More specifically, the process provides for the production of phosphoric acid, ammonium phosphate and useful by-products utilizing synthesis gas and air to produce oxalic acid and ammonia. The synthesized oxalic acid is utilized for phosphate rock digestion to produce phosphoric acid, which can be reacted with ammonia to produce ammonium phosphate. Calcium oxalate from phosphate rock digestion is utilized to produce calcium carbonate, ammonium oxalate and oxamide.

Process for manufacturing ammonium phosphate utilizing an oxalic acid

A method of producing purified monoammonium phosphate from wet process phosphoric acid and ammonia is provided. The ammoniation takes place in two stages, the acid being ammoniated in the first stage to a pH between about 1.5 and 2.5. This mixture is allowed to age after which the mixture is ammoniated to a pH between about 4 and 5. An impurity-containing precipitate is formed in the first and second stages of ammoniation that is easily filterable from the monoammonium phosphate solution derived from the second ammoniation stage.

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Prairieville, LA, United States of America

Charles W Weston